This application claims the priority of German patent application 101 11 562.8, filed 10 Mar. 2001, the disclosure(s) of which is (are) expressly incorporated by reference herein.
The invention relates to a method for operating a load-dependent power-generating system in a vehicle.
European patent document EP 0633 157 B1 discloses a method of the generic type for dynamically controlling the performance of a fuel cell unit in vehicles with an electric drive motor. A performance setpoint value for the fuel cell unit is determined from the accelerator pedal position, and the performance of the fuel cell unit is controlled by controlling the mass flow rate of the oxidant which is fed to the fuel cell unit. In order to prevent the electric drive motor""s requesting more performance from the fuel cell unit than it can supply at a given time, the electric drive motor is supplied with a corrected performance setpoint value which is determined from the actual oxidant mass flow rate.
German patent document DE 195 41 575 C2 discloses a method for determining a power setpoint value for a load-dependent power-generating system (in particular for a fuel cell system) in an electric vehicle, in which setpoint values for the motor train currents of the electric drive motor are determined on the basis of the accelerator pedal position. The performance setpoint value for the power-generating system is generated from the setpoint values for the motor train currents of the electric drive motor.
One object of the present invention is to improve the dynamic behavior of the control methods described previously.
This and other objects and advantages are achieved by the control method according to the invention for operating a load dependent power-generating system that supplies electric energy to at least one electric drive motor in a vehicle. A performance setpoint value is determined for the electric drive motor from an accelerator pedal position, and a power request is made to the power-generating system before a torque request to the drive motor. Dynamic movement parameters of the accelerator pedal are also used to calculate the performance setpoint value.
The advantage of the invention is that the evaluation of the accelerator pedal movement/position permits a predictive calculation of the performance setpoint value. In this manner, the time delay between the requested performance and the running up or running down of the power-generating system can be bridged. As a result of the earlier request of the predictively calculated, future performance, the power-generating system has more time to generate the drive current, and the electric drive motor can reach the level of performance desired by the driver more quickly and more dynamically. Taking into account the accelerator pedal movement leads to an improvement in the dynamics in comparison with methods which use only the accelerator pedal position.
Of course, the features which are mentioned above and which are to be explained below can be used not only in the respectively given combination but also in other combinations or alone without departing from the scope of the present invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.